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greg |
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/* Copyright (c) 1991 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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/* |
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* Generate an N-dimensional Peano space-filling curve |
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* on the interval [0,1). |
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* |
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* 12 Aug 91 Greg Ward |
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*/ |
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extern double floor(); |
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static double |
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peanoC(n, t, e) /* compute Peano coordinate */ |
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int n; |
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double t, e; |
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{ |
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register int i; |
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double d; |
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if (e >= 1./3.) |
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return(t); |
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d = 0.; |
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while (t-d >= 1./3.) |
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d += 1./3.; |
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i = n; |
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while (--i > 0) |
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t *= 3.; |
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t = 3.*(t - floor(t)); |
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i = 0; |
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while (t >= 1.) { |
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t -= 1.; |
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i ^= 1; |
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} |
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t = peanoC(n, t, 3.*e); |
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if (i) |
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t = 1. - t; |
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return(d + t/3.); |
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} |
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peano(p, n, t, e) /* compute Peano point */ |
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double p[]; |
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int n; |
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double t, e; |
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{ |
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register int i; |
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int neg = 0; |
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i = n; |
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while (i-- > 0) { |
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p[i] = peanoC(n, t, e); |
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if (neg) |
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p[i] = 1. - p[i]; |
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t *= 3.; |
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while (t >= 1.) { |
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t -= 1.; |
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neg ^= 1; |
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} |
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} |
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} |
